Question

A 60.0-kg woman jumps from a burning building and falls 10.0 m before making contact with a safety net, which stops her in 0.120 s. What is the average force exerted by the net on her? (not in sig fig)

Answer 1

Given:

The mass of the women is m = 60 kg

The height of the building is h = 10 m

The time duration is t = 0.12 s

Required: Average force exerted by the net on the women.

Explanation:

First, we need to calculate the speed by the formula

$v=\sqrt{2gh}$

Here, g = 9.8 m/s^2 is the acceleration due to gravity.

On substituting the values, the speed of the car will be

$\begin{gathered} v=\sqrt{2\times9.8\times10} \\ =14\text{ m/s} \end{gathered}$

The impulse can be calculated as

$\begin{gathered} Impulse\text{ = change in momentum} \\ =m(v-0) \\ =60\times14 \\ =840\text{ kg m/s} \end{gathered}$

The average force can be calculated as

$\begin{gathered} Impulse\text{ = F}\times t \\ F=\frac{Impulse}{time} \\ =\frac{840}{0.12} \\ =7000\text{ N} \end{gathered}$

Final Answer: The average force exerted by the net on her is 7000 N